Self-contained multi-blade package and assembly utilizing same

ABSTRACT

A self-contained multi-blade package is constructed and arranged to be mounted in the blade head assembly of a wafering machine wherein opposite end portions of the blades are clamped for tensioning the blades, the blade package being preassembled with connecting rods extending through aligned holes of rectangular spacer plates and end plates which extend above and below the blades to provide shoulders to be gripped by tensioning shoulders in the blade head assembly, the holes in the plates being located in offset relation to clamping areas against which clamping blocks of the head assembly thrust in clamping the blades for efficient tensioning of the blades in the blade head assembly.

United States Patent Ranieri 1 SELF-CONTAINED MULTl-BLADE PACKAGE AND ASSEMBLY UTILIZING SAME [76] Inventor: Louis F. Ranieri, 8423 N. Clifton St.. Niles. lll. 60648 [22] Filed: July 2, 1973 [21] App]. No: 375,389

Related U.S. Application Data [63] Continuation-impart of Ser. No. 79.947, Oct l2,

l970, Pat. No. 3.742,8U5.

Italy l25/l8 June 17, 1975 Primary Examiner-Harold D. Whitehead Attorney, Agent, or Firm-Hill, Gross, Simpson Van Santen, Steadman. Chiara & Simpson [57] ABSTRACT A self-contained multi-blade package is constructed and arranged to be mounted in the blade head assembly of a wafering machine wherein opposite end portions of the blades are clamped for tensioning the blades, the blade package being preassembled with connecting rods extending through aligned holes of rectangular spacer plates and end plates which extend above and below the blades to provide shoulders to be gripped by tensioning shoulders in the blade head assembly, the holes in the plates being located in offset relation to clamping areas against which clamping blocks of the head assembly thrust in clamping the blades for efficient tensioning of the blades in the blade head assembly.

5 Claims, 6 Drawing Figures PATENTEDJUH 17 1975 889699 1 SELF-CONTAINED MULTI-BLADE PACKAGE AND ASSEMBLY UTILIZING SAME This application is a continuation-in-part of my copending application Ser. No. 79,947 filed Oct. 12, 1970 now US. Pat. No. 3,742,805, issued July 3, 1973.

The present invention relates to self-contained, multi-blade assembly packages and is more particularly concerned with the construction and arrangement of such blade packages for efficient mounting and tensioning in a wafering machine blade head assembly.

Heretofore it has been the practice either to assemble the blades and spacers individually into the blade head assembly of a wafering machine, or to provide a blade package in which the blades and spacers are secured together by some sort of bonding means such as a thermo-setting or other adhesive. Both of these arrangements have serious deficiencies and disadvantages.

Where the blades and spacers are mounted as individual elements in the blade head assembly, much time and effort is consumed, parts are easily lost. Further, when it is desired to invert the blades, the entire process must be repeated, to, in effect, rebuild the blade assembly. Salvaging of parts of the asembly is extremely difficult and generally ignored, even though considerable savings could be effected if salvaging of undamaged, unbroken and still usable parts were to be effected.

Since it is extremely important to attain great accuracy in spacing of the blades for uniformity of wafering results, the bonding method of attaining a selfcontained package presents a rather serious problem in that the adhesive material between the spacers and the blades can hardly be controlled to the extent that there may not be at least minute but nevertheless significant variations in spacing between the blades after the package has been clamped in the blade head assembly. In addition, the bonding technique requires special ban dling to effect the bonding which not only entails use of special equipment, but involves a rather costly labor problem due to the processing required, and only narrow blade packages are feasible.

It has also been proposed, for example in US. Pat. No. 3,263,669 to provide a pre-assembled blade package wherein circular disk spacers and end plates are provided and a central rod extends through the plates and through holes in the end portions of the blades. However, that arrangement has not proved satisfactory in practice. There is no substitute for square shouldering of the spacer and end plate assemblies in the blade head assembly for efficient tensioning. In the cylindrical arcuate shouldering necessary in the arrangement of said patent, not only is it difficult to provide for the necessary close tolerances for uniform shouldering contact to attain effective uniform tensioning of the blades, but the problem of excessive wear at the bearing points is encountered. Further, the blade package with the circular disk spacers cannot be used in the existing blade head assemblies having square tensioning shoulders.

An important object of the present invention is to overcome the foregoing and other disadvantages, deficiencies. inefficiencies, shortcomings and problems in prior expedients and to provide a new and improved self-contained. multi-blade package embodying principles of the present invention, as will hereinafter become apparent.

Another object of the invention is to provide a simplified, efficient multi-blade package assembly for the intended purpose.

A further object of the invention is to provide a new and improved self-contained, multi-blade package for the intended purpose which facilitates salvaging of reusable elements thereof.

Yet another object of the invention is to provide new and improved means for efficiently clamping the blades of a rod-connected self-contained, multi-blade package assembly in a blade head assembly of a wafering machine.

Other objects, features and advantages of the invention will be readily apparent from the following description of certain preferred embodiments, taken in conjunction with the accompanying drawings, although variations and modifications may be effected without departing from the spirit and scope of the novel concepts exemplified in the disclosure, and in which:

FIG. 1 is a perspective view of a blade head assembly in which a self-contained, multi-blade package embodying features of the present invention is mounted.

FIG. 2 is a sectional detail view taken substantially along the line ll-lI of FIG. 1.

FIG. 3 is a sectional detail view taken substantially along the line IllIIl of FIG. 1.

FIG. 4 is an enlarged fragmental sectional detail view taken substantially along the line IV|V of FIG. 2.

FIG. 5 is an enlarged fragmentary side elevational view of the blade package taken substantially along the line VV of FIG. 4; and

FIG. 6 is a fragmentary side elevational view of a blade package showing a modification utilizing two connecting rods instead of one connecting rod.

Wafering machines in which a multi-blade package 10 (FIGS. 1-5) or 10' (FIG. 6), embodying features of the present invention, is adapted to be used comprise a base supporting a pair of ways generally disposed in a horizontal plane and arranged to support reciprocably a blade head assembly 11 in suitable manner to be driven by a suitable motor. The blade head assembly 11 comprises a rectangular frame comprising opposite spaced side bars or rails 12 connected together at one end by an end frame bar assembly 13 secured thereto as by means of screws 14. At their opposite ends, the side frame bars 12 are secured together by an end frame bar 15 secured thereto as by means of screws 17. Suitable means (not shown) are provided for supporting the frame 11 for reciprocation on the ways of the machine for reciprocal sawing movement.

Means are provided for supporting the blade package 10 within the frame 11 in a horizontal position substantially vertically centered midway between the top and bottom planes of the massive frame and with identical elongated hardened thin strip steel blades 18 of the blade assembly uniformly tensioned between the end bars 13 and 15. For this purpose, the blades are assembled together in coextensive relation with vertically elongated rectangular spacer plates 19 intervening between the opposite end portions of the blades. So that the blade package 10 can be handled and assembled with the head assembly 11 as a self-contained unit, the spacers 19, respective end thrust plates 20 at opposite sides and aligned with and coextensive with the spacers l9 and the blades 18 are connected together by means of rods 21 extending through suitable aligned holes 21a in the plates and the blades. Desirably, the rods 21 are only as strong as necessary to resist deformation from the weight of the assembly and are desirably of as small a diameter as practicable so as to occupy minimum of the blade and spacer area and so that aligned rodreceiving holes in the blades and in the spacers and end plates may be as small diameter as possible to avoid weakening of the affected areas of the parts. While the rods 21 may be in the form of narrow shank headed bolts, a practical. economical arrangement comprises having the rods threaded at their respective opposite ends and engaged by respective retaining nuts 22. These nuts are driven clampingly toward one another and against the end thrust plates 20 which are thicker and heavier stock than the spacers 19 to resist distortion but are preferably of the same dimensions in outline. As best seen in FIGS. 2 and 5, the spacers l9 and the end plates 20 are desirably vertically elongated as related to the blades which extend horizontally, and with preferably equal upper and lower portions of the coextensive spacers and end plates providing square tensioning shoulders 23 facing inwardly relative to the blade package assembly.

For tensioning engagement with the blade package shoulders 23, the blade head assembly 11 has complementary oppositely facing tensioning shoulders. As best seen in FIGS. 2 and 4, at one end of the assembly 11 tensioning shoulders 24 are provided by and within the frame end bar 13 which in order to permit convenient assembly of the blade package is made in the form of a pair of complementary upper and lower frame bars 25 and 27 suitably recessed to provide the shoulders 24 and a clearance gap therebetween for the saw blades 18. The construction and relationship of the end bar sections 25 and 27 is such that the upper bar section 25 can be readily separated from the lower bar section 27 which is fixedly secured by the screws 14 to the side bars 12. For this purpose the interface of the bar sections 25 and 27 is provided with a stepped shoulder structure 28 for positive alignment and anchorage, and a plurality of screws 29 extend vertically through the bar section 25 and secure it to the bar section 27 after the shouldering end structure of the blade package has been dropped into place in the recess adjacent to the shoulder 24 in the lower bar section 27.

While the bar 13 is stationary, and the bar at the opposite end of the blade head assembly is also stationary, a tensioning bar 30 generally complementary to the bar 13, but tensionably movable relative to the bar 15 is provided. This comprises a lower bar section 31 and an upper bar section 32 which in assembly are aligned and interlocked by a stepped shoulder interface structure 33. Complementary recessing of the bar sections 31 and 32 provide tensioning shoulders 34 which are engaged by the shoulders 23 of the associated end portions of the blade package 10, there being an ample clearance leading from the shoulders 34 for the saw blades 18. After the blade package has been assembled with the lower bar section 31, the upper bar section 32 is placed in position and is secured fixedly by means of screws 35.

Blade tensioning pull on the bar 30 is effected by tensioning screws 37 which are threaded into blind end bores 37a in the lower bar section 31 and on axes which lie in a horizontal plane with the horizontal midplane through the blades 18. By tightening the screws 37 by means of a suitable wrench applied to their heads 38 projecting outwardly from the bar 15 and provided with wide shoulders 39 against the bar 15, to draw the bar 30 toward the bar 15, a powerful pulling tensioning force is applied to the blades 18 between the bars 13 and 30 to maintain the blades stretched taut parallel for sawing an ingot or large quartz crystal or other mineral into wafers of the desired thickness. In tensioning the blades. sufficient force is applied to virtually tune the blades similarly as a piano string, and an experienced operator mechanic can tell when the blades are sufficiently tensioned by twanging the blades to determine whether they resonate to a certain freqency. All of the blades must be evenly tensioned so that they will vibrate at the same frequency otherwise they will vibrate against each other and cause variance in dimensions and fall outside of acceptable wafering tolerances. After the blades have been tensioned, they are placed in cutting engagement with a mineral piece to be wafered, with relative vertical pressure applied between the mineral and the blades, and a slurry of microscopic abrasive material supplied to the cutting edges of the blades to effect the actual cutting. It will be observed that since the blades 18 are double-edged, after they have worn down along one edge, the blade package can be removed and inverted so that the opposite edges of the blades are placed into working position. This can be very readily accomplished by reason of the blade package 10 being secured by the rods 21 to be handled as a unit. Should any blade for any reason break, it can be readily replaced where that is feasible, such as where the edges of the blades in the package along one face plane remain unused.

Tensioning force applied by the screws 37 is generally on the order of 2000 to 5000 pounds depending on the number of blades in the blade package 10. Such tensioning force is far beyond anything the rods 21 or the blades 18 could possibly withstand if the tensioning force were applied through the rods. The sole function of the rods 21, therefore, is to maintain the blade pack age 10 preassembled for convenient handling, and adequate clearance is provided in the holes 21a through the blades 18 through which the rods 21 extend to permit the slight relative longitudinal adjustments that may be necessary in the blades during tensioning. What is relied upon to hold the blades against slipping from a uniformly taut condition as tensioned, is transverse compression which drives the blades and spacers 19 as well as the end plates 20 into a secure frictional bond. For this purpose, compression screws 40 (FIGS. 3 and 4) extend through threaded bores 41 provided in one of the sides of the bars 27 and 31, and extending through one of the side rails 42 on each of such bars by which they are horizontally aligned along longitudinal track grooves 43 provided in the inner sides of the side bars 12. In a desirable form, the compression screws 40 are on the order of large set screws of the recessed socket head type arranged to be turned into compressing thrust or backed off as by means of hex wrenches 44 (FIGS. 1 and 3) extended through a suitable clearance hole 45 aligned with the screw 40 in the side bar 12. at the stationary anchorage end of the head assembly, and a longitudinally elongated clearance hole 47 aligned with the screw 40 at the tensioning end of the head assembly. For applying compression force to the end portions of the blade package 10, each of the screws 40 has a flat thrusting tip 48 which engages against a clamping block 49 of substantially greater thickness than the end plates and of complementary length and width whereby to make thorough face-toface engagement with the contiguous end plates 20. At the opposite side of the blade package preferably identical compression blocks 50 are provided in faceto-face compression engagement with the end plates at that side of the package. To fill out between the compression blocks 50 and the adjacent walls within the recess of the bars 27 and 31, a shim or spacer block or piece 51 may be provided when necessary. The thickness of the piece 51 will be accommodated to the width of the blade package 10. To assure the face-to-face engagement of the compression blocks 49 and 50 with the end plates 20, the blocks 49 and 50 are provided with suitable respective recesses 52 to receive and clear the nuts 22 and the projecting end portions of the rods 21, such end portions being preferably calculated to project only a minimum distance from the nuts or clipped off to such a minimum distance. As will be ob served, the clearance recesses 52 are blind end and do not extend through the opposite faces of the blocks 49 and 50, to avoid any weakening in the thrust-receiving faces of the blocks. The blocks are of sufficient thickness to avoid any necessity for projection of the ends of the rods from the thrust-receiving faces so that those faces are perfectly plane to receive the large thrust tips 48 of the compression screws thereagainst as exemplified in FIG. 5 where the area of engagement of the thrust tip 48 is shown in dot-dash outline.

As will be observed from FIGS. 2, 4 and 5, because of the limitation on width of the spacers 19, the end plates 20 and the compression blocks 49 and 50, the thrust area to which the compression screw tip 48 is applied at each end of the blade package 10 is limited in the direction of longitudinal tensioning resistance of the blades 18. Therefore, maximum use of the compression area must be made in order to attain the necessary frictional retention of the blades 18 between the spacers 19 for uniform maximum tensioning.

At first. it was thought that by having the connecting rods 21 centered between the longitudinal edges of the spacers 18 and the end plates 20 best results would be obtained because then, as would be normally assumed, pressure applied by the compression screws 40 would be nicely balanced at each opposite side of the rods and the holes through which the rods 21 extend in the assembled parts. It was found, however, that even with maximum compression applied by the compression screws, blade failure was experienced. Critical examination and analysis revealed that the breaks in the failed blades occured at the narrow area above or below the rod passage hole in the blade due to greater slippage than provided for in tolerance differential in hole size relative to rod diameter. Sometimes when one blade failed there would be a chain reaction so that several of the blades would break, all showing the same breakage pattern. The indication was clear that the rods 21 themselves could not be relied upon to hold the blades or any of them under tension. It also revealed that the stretching of the blades placed an intolerable stress on the narrow connecting areas of the blades above and below the rod passage holes. It was therefore evident that either the rod connection would have to be abandoned or a more secure frictional interengagement of the parts attained. There is a point beyond which additional compression thrust force is impractical due to warpage and other stresses imposed on the material of the parts. Satisfactory compression within safe stress limits is about 20 pounds per blade in the package. The narrow space between the vertical edges of the spacers l9 and end plates 20 available for compression area therefore presented a critical problem. It was then discovered by experimentation that offsetting the rods 21 and thereby the passage holes as close as practicable to the outer vertical edges of the spacers 19 and the end plates 20, that is toward the ends of the blades 18, thus increasing the friction compression areas of the spacers and end plates between the holes and the edges defining the tensioning shoulders 23, the problem of blade breakage was solved. While it might seem at first that adding such a small area to thrusting frictional compression of the compression screws between the shoulder edges and the rod passage holes should not make that much difference in results, it was nevertheless discovered that adding this small additional compression area did and does solve the problem so that the tensioning stretching of the blades with from 2000 to 5000 pounds pull, depending on the number of blades in the blade package, breakage by fracture at the rod passage holes has been eliminated, even though the holes are held to fairly close tolerance size differential relative to the rod diameters so as to retain as much solid blade surface as practicable.

Another satisfactory manner of overcoming the problem of inadequate frictional pressure area between the blades and the spacers and end plates even where one of the spacers 19' is interposed between the end plate 20' and the adjacent outermost blade 18', is depicted in FIG. 6 wherein the blade package 10' has retaining rods 21 thoroughly offset from the area of compression pressure to be applied by the compression screws in the blade head assembly. in this modification, the retaining rods 21' are located in spaced relation above and below the blades 18' leaving the area between the rods free for application of the compression screw pressure directly to the maximum friction area afforded between the vertical edges of the aligned spacers l9 and end plates 20', the rods extending through aligned passage holes in the spacers and end plates only and securing them in retaining clamping engagement with the interposed blades 18 by action of the retaining nuts 22'. While this arrangement does have the advantage of maximum freedom of frictional compression area between the spacers and the blades, there is some problem with maintaining the blades and the spacer and end plate assembly properly aligned during handling, and especially rough handling, which is not encountered with the arrangement in FIG. 5 where the blades 18 cannot displace significantly relative to the spacers and end plates because the rods 21 extend through the blades as well as the spacers and end plates. Nevertheless, in the arrangement of FIG. 6, when the compression is applied to the blade package assembly, thorough, break-free engagement and holding of the blades 18' under operating tension is attained.

When setting up the blade package 10 in the blade head assembly 11, after the blade package has been inserted and the tension bars 25 and 32 secured in place, equalized tightening of the blades is facilitated in the initial adjustments relative to the blade package in the blade head assembly. Initially, the clamping blocks 49 and 50 are relatively lightly tightened against the blade assembly by means of the compression screws 40, whereafter the stretching bar 30 is operated in cooperation with the stationary bar 13, by means of the screws 37 to begin stretching the blades l8 to cause the less taut blades to stretch while the more taut blades may slip somewhat relative to the spacers or end plates to attain equalized tension. Then the clamping blocks 49 are fully tightened by means of the compression screws 40 to completely lock the blades and the spacers and end plates frictionally into a functionally integral unit. Stretching of the blades is then completed to attain the final uniform tensioning of the blades.

It will be understood that variations and modifications may be effected without departing from the spirit and scope of the novel concepts of this invention.

1 claim:

1. A self-contained, preassembled, multi-blade package for mounting in a blade head assembly of an existing wafering machine having square tensioning shoulders and wherein opposite end portions of the blades are clamped under pressure between clamping blocks for unison tensioning of the blades by said shoulders, comprising:

a plurality of substantially coextensive elongated thin flat strip blades in side-by-side assembly and having opposite end portions;

elongated rectangular spacer plates aligned with one another and disposed between aligned end portions of the blades. and having small diameter aligned holes;

elongated rectangular end plates generally coextensive with and aligned with the spacer plates at the opposite sides of the blade package and having aligned holes aligned with the holes of the spacer plates;

said spacer plates and said end plates having their longitudinal edges transverse to the longitudinal edges of the blades and extending substantially beyond the opposite planes across the edges of the blades and thereby providing square shoulders along the combined edges of the plates which face away from the adjacent ends of the blades for engagement with the square tensioning shoulders of the blade head assembly;

connecting rods extending through the aligned holes of the spacer plates and end plates;

means on the respective opposite end portions of said rods retaining the spacer plates and end plates and blades assembled with the rods so that the blade package can be handled as a self-contained unit for mounting in and removal from the blade head assembly;

said clamping blocks at each opposite side of the blade package being of elongated rectangular shape generally coextensive with and matching the size of the spacer plates and end plates. the blocks having a longitudinal axis transverse to the edges of the blades and extending substantially beyond the opposite planes across the edges of the blades the same as said spacer plates and end plates and pro viding square shoulders in the plane of the plate shoulders and facing away from the adjacent ends of the blades. the clamping blocks having in their faces which engage the end plates recesses just large enough to receive ends of the connecting rods and said retaining means freely and with opposite faces of the clamping blocks being unbroken to receive full thrust of the ends of compression screws of the head assembly thereagainst:

and said rods and said holes in the plates and said recesses in said blocks being eccentric to the plates and blocks and being located in substantial eccentric offset clearance relation with respect to maximum available unobstructed solid frictional compression thrust areas in the aligned portions of the blades and plates and clamping blocks all the way across the blade package at each of said end portions, and which areas extend throughout the widths of the blades and extend from the shoulder edges of the plates and blocks throughout at least one half the width of the plates and blocks, for re ceiving maximum frictional clamping thrust value from blade head assembly compression screws driven against the clamping blocks;

whereby to enable maximum tensioning of the blades with freedom from liability of slipping and breaking of any blade in the package during said maximum tensioning, while permitting said rods to remain continuously in place in the package to maintain the benefit of the rod connection for handling of the package.

2. A blade package according to claim 1, wherein said end portions of the blades have holes therein aligned with the holes in said plates, and said rods extend through the holes in both the plates and the blade end portions and are eccentrically offset from the shoulder edges toward the adjacent ends of the blades and are thereby located substantially beyond the longitudinal center between the opposite longitudinal edges of the plates and substantially closer to the plate edges which are nearer the adjacent ends of the blades than to said shoulder edges.

3. In combination with a blade head assembly of a wafering machine wherein said assembly includes a rectangular frame arranged to be supported for motordriven reciprocation in a wafer cutting machine and having tensioning bars providing blade stretching shoulders:

a self-contained, preassembled, multi-blade package mounted in the blade head assembly and comprising a plurality of substantially coextensive elongated thin flat strip blades in side-by-side assembly and having opposite end portions;

elongated rectangular spacer plates aligned with one another and disposed between aligned end portions of the blades, and having small diameter aligned holes;

elongated rectangular end plates generally coextensive with and aligned with the spacer plates at the opposite sides of the blade package and having aligned holes aligned with the holes of the spacer plates;

said spacer plates and said end plates having their longitudinal axes transverse to the edges of the blades and extending substantially beyond the opposite planes across the edges of the blades and thereby providing square shoulders along their combined edges which face away from the adjacent ends of the blades with the shoulders engaging the tensioning shoulders of the head assembly;

connecting rods extending through the aligned holes of the spacer plates and end plates and having means on the respective opposite end portions of the rods retaining the spacer plates and end plates and blades assembled with the rods so that the blade package can be handled as a self-contained unit for mounting in and removal from the blade head assembly;

and clamping blocks at each opposite side of the blade package and being of elongated rectangular shape generally coextensive with and matching the size of the spacer plates and end plates, the blocks having a longitudinal axis transverse to the edges of the blades and extending substantially beyond the opposite planes across the edges of the blades the same as said spacer plates and end plates and providing square shoulders in the plane of the plate shoulders and facing away from the adjacent ends of the blades, the clamping blocks having in their faces which engage the end plates recesses just large enough to receive ends of the connecting rods and said retaining means freely and with opposite faces of the clamping blocks being unbroken to receive full thrust of the ends of compression screws of the head assembly thereagainst;

said rods and said holes in the plates and said recesses in the blocks being eccentric to the plates and blocks and being located in substantially eccentric offset clearance relation to maximum available unobstructed solid frictional compression thrust areas in the aligned portions of the blades and plates and clamping blocks all the way across the blade package at each of said end portions, and which areas extend throughout the widths of the blades and extend from the shoulder edges of the plates and blocks throughout at least one half the width of the plates and blocks for receiving maximum frictional clamping thrust value from said compression screws driven against the clamping blocks; whereby to enable maximum tensioning of the blades by said tensioning bars with freedom from liability of slipping and breaking of any blade in the package during said maximum tensioning, while permitting said rods to remain continuously in place in the package for maintaining the benefits of the rod connection for handling of the package when released from the tensioning bars and clamping blocks.

4. A combination according to claim 3, wherein said end portions of the blades have holes therein aligned with the holes in said plates, and said rods extend through the holes in both the plates and the blade end portions and are eccentrically offset from the shoulder edges toward the adjacent ends of the blades and are thereby located substantially closer to the plate edges which are nearer the adjacent ends of the blades than to said shoulder edges so that the clamping areas are located on the larger part of the plates and clamping blocks disposed between the holes and rods on the one hand and the shoulder edges on the other hand.

5. A combination according to claim 4, wherein said holes and rods are located in eccentrically offset relation from said shoulder edges substantially beyond the longitudinal center between the opposite longitudinal edges of the plates and as close as practicable to the plate edges nearest the adjacent ends of the blades. 

1. A self-contained, preassembled, multi-blade package for mounting in a blade head assembly of an existing wafering machine having square tensioning shoulders and wherein opposite end portions of the blades are clamped under pressure between clamping blocks for unison tensioning of the blades by said shoulders, comprising: a plurality of substantially coextensive elongated thin flat strip blades in side-by-side assembly and having opposite end portions; elongated rectangular spacer plates aligned with one another and disposed between aligned end portions of the blades, and having small diameter aligned holes; elongated rectangular end plates generally coextensive with and aligned with the spacer plates at the opposite sides of the blade package and having aligned holes aligned with the holes of the spacer plates; said spacer plates and said end plates having their longitudinal edges transverse to the longitudinal edges of the blades and extending substantially beyond the opposite planes across the eDges of the blades and thereby providing square shoulders along the combined edges of the plates which face away from the adjacent ends of the blades for engagement with the square tensioning shoulders of the blade head assembly; connecting rods extending through the aligned holes of the spacer plates and end plates; means on the respective opposite end portions of said rods retaining the spacer plates and end plates and blades assembled with the rods so that the blade package can be handled as a self-contained unit for mounting in and removal from the blade head assembly; said clamping blocks at each opposite side of the blade package being of elongated rectangular shape generally coextensive with and matching the size of the spacer plates and end plates, the blocks having a longitudinal axis transverse to the edges of the blades and extending substantially beyond the opposite planes across the edges of the blades the same as said spacer plates and end plates and providing square shoulders in the plane of the plate shoulders and facing away from the adjacent ends of the blades, the clamping blocks having in their faces which engage the end plates recesses just large enough to receive ends of the connecting rods and said retaining means freely and with opposite faces of the clamping blocks being unbroken to receive full thrust of the ends of compression screws of the head assembly thereagainst; and said rods and said holes in the plates and said recesses in said blocks being eccentric to the plates and blocks and being located in substantial eccentric offset clearance relation with respect to maximum available unobstructed solid frictional compression thrust areas in the aligned portions of the blades and plates and clamping blocks all the way across the blade package at each of said end portions, and which areas extend throughout the widths of the blades and extend from the shoulder edges of the plates and blocks throughout at least one half the width of the plates and blocks, for receiving maximum frictional clamping thrust value from blade head assembly compression screws driven against the clamping blocks; whereby to enable maximum tensioning of the blades with freedom from liability of slipping and breaking of any blade in the package during said maximum tensioning, while permitting said rods to remain continuously in place in the package to maintain the benefit of the rod connection for handling of the package.
 2. A blade package according to claim 1, wherein said end portions of the blades have holes therein aligned with the holes in said plates, and said rods extend through the holes in both the plates and the blade end portions and are eccentrically offset from the shoulder edges toward the adjacent ends of the blades and are thereby located substantially beyond the longitudinal center between the opposite longitudinal edges of the plates and substantially closer to the plate edges which are nearer the adjacent ends of the blades than to said shoulder edges.
 3. In combination with a blade head assembly of a wafering machine wherein said assembly includes a rectangular frame arranged to be supported for motor-driven reciprocation in a wafer cutting machine and having tensioning bars providing blade stretching shoulders: a self-contained, preassembled, multi-blade package mounted in the blade head assembly and comprising a plurality of substantially coextensive elongated thin flat strip blades in side-by-side assembly and having opposite end portions; elongated rectangular spacer plates aligned with one another and disposed between aligned end portions of the blades, and having small diameter aligned holes; elongated rectangular end plates generally coextensive with and aligned with the spacer plates at the opposite sides of the blade package and having aligned holes aligned with the holes of the spacer plates; said spacer plates and said end plates having their longitudinal axes transverse to the edges of the Blades and extending substantially beyond the opposite planes across the edges of the blades and thereby providing square shoulders along their combined edges which face away from the adjacent ends of the blades with the shoulders engaging the tensioning shoulders of the head assembly; connecting rods extending through the aligned holes of the spacer plates and end plates and having means on the respective opposite end portions of the rods retaining the spacer plates and end plates and blades assembled with the rods so that the blade package can be handled as a self-contained unit for mounting in and removal from the blade head assembly; and clamping blocks at each opposite side of the blade package and being of elongated rectangular shape generally coextensive with and matching the size of the spacer plates and end plates, the blocks having a longitudinal axis transverse to the edges of the blades and extending substantially beyond the opposite planes across the edges of the blades the same as said spacer plates and end plates and providing square shoulders in the plane of the plate shoulders and facing away from the adjacent ends of the blades, the clamping blocks having in their faces which engage the end plates recesses just large enough to receive ends of the connecting rods and said retaining means freely and with opposite faces of the clamping blocks being unbroken to receive full thrust of the ends of compression screws of the head assembly thereagainst; said rods and said holes in the plates and said recesses in the blocks being eccentric to the plates and blocks and being located in substantially eccentric offset clearance relation to maximum available unobstructed solid frictional compression thrust areas in the aligned portions of the blades and plates and clamping blocks all the way across the blade package at each of said end portions, and which areas extend throughout the widths of the blades and extend from the shoulder edges of the plates and blocks throughout at least one half the width of the plates and blocks for receiving maximum frictional clamping thrust value from said compression screws driven against the clamping blocks; whereby to enable maximum tensioning of the blades by said tensioning bars with freedom from liability of slipping and breaking of any blade in the package during said maximum tensioning, while permitting said rods to remain continuously in place in the package for maintaining the benefits of the rod connection for handling of the package when released from the tensioning bars and clamping blocks.
 4. A combination according to claim 3, wherein said end portions of the blades have holes therein aligned with the holes in said plates, and said rods extend through the holes in both the plates and the blade end portions and are eccentrically offset from the shoulder edges toward the adjacent ends of the blades and are thereby located substantially closer to the plate edges which are nearer the adjacent ends of the blades than to said shoulder edges so that the clamping areas are located on the larger part of the plates and clamping blocks disposed between the holes and rods on the one hand and the shoulder edges on the other hand.
 5. A combination according to claim 4, wherein said holes and rods are located in eccentrically offset relation from said shoulder edges substantially beyond the longitudinal center between the opposite longitudinal edges of the plates and as close as practicable to the plate edges nearest the adjacent ends of the blades. 